CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (USD $) In Thousands, unless otherwise specified	Total	PREFERRED SHARES	COMMON SHARES, $0.01 PAR VALUE	PAID IN CAPITAL	RETAINED EARNINGS	ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME	OPERATING PARTNERSHIP	Partially Owned Properties [Member]
Beginning Balance, Parent at Dec. 31, 2012	$ 7,289,813	$ 50,000	$ 3,251	$ 6,542,355	$ 887,355	$ (193,148)
Beginning Balance, Noncontrolling Interest	316,532						209,039	107,493
Common Share Issuance:
Conversion of OP Units held by Noncontrolling Interests into OP Units held by General Partner				979			(979)
Issuance of Common Shares			345	1,929,523
Exercise of share options			5	13,880
Stock Issued During Period, Value, Employee Stock Purchase Plan				2,363
Share-based employee compensation expense:
Restricted shares			2	6,884
Share options				6,688
ESPP discount				449
Offering costs				(744)
Supplemental Executive Retirement Plan (SERP)				(671)
Change in market value	(33,039)			33,039
Adjustment for Noncontrolling Interests ownership in Operating Partnership				(38,718)			38,718
Net income attributable to controlling interests	1,342,445				1,342,445
Common Share distributions					(288,130)
Dividends, Preferred Stock, Cash					(2,072)
Accumulated other comprehensive (loss) income - derivative instruments:
Unrealized holding (losses) arising during the period	12,337					12,337
Losses reclassified into earnings from other comprehensive income	12,098					12,098
Accumulated other comprehensive income (loss) - other instruments:
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	928					928
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	941					941
Issuance of LTIP Units to Noncontrolling Interests							5
Equity Compensation associated with Noncontrolling Interests							9,514
Net Income (Loss) Attributable to Noncontrolling Interest							56,111	(790)
Contributions by Noncontrolling Interests								6,769
Archstone Acquisition Noncontrolling Interests Partially Owned Properties								28,263
Distributions to Noncontrolling Interests							(11,379)	(4,437)
Change in carrying value	42,557						(42,557)
Ending Balance, Noncontrolling Interest at Jun. 30, 2013	316,532						209,039	107,493
Ending Balance, Parent at Jun. 30, 2013	$ 10,322,384	$ 50,000	$ 3,603	$ 8,496,027	$ 1,939,598	$ (166,844)